An envelope used in voting by mail includes a signature area on which the signature is affixed and a concealing portion structured to cover the signature area thereby concealing the signature. The concealing portion includes a concealing layer that is preferably positioned on top of a protective layer. The protective layer is positioned between the signature area and the concealing layer when the concealing portion covers the signature area. The concealing layer is formed from a material that is normally opaque but becomes at least partially transparent when one or more chemicals are applied to the concealing layer. The protective layer protects the signature from the one or more chemicals since the protective layer is impermeable to the one or more chemicals.